This invention relates to an antifoam composition including particulate material, the particulate material of the antifoam composition having adhered thereto an antimicrobial agent which functions to prevent bacterial spoilage.
Antimicrobial agents are chemical compositions that are used to prevent microbiological contamination and deterioration of products, materials, and systems. Particular areas of application of antimicrobial agents and compositions are, for example, cosmetics, disinfectants, sanitizers, wood preservation, food, animal feed, cooling water, metalworking fluids, hospital and medical uses, plastics and resins, petroleum, pulp and paper, textiles, latex, adhesives, leather and hides, and paint slurries. Of the diverse categories of antimicrobial agents and compositions, quaternary ammonium compounds represent one of the largest of the classes of antimicrobial agents in use. At low concentrations, quaternary ammonium type antimicrobial agents are bacteriostatic, fungistatic, algistatic, sporostatic, and tuberculostatic. At medium concentrations they are bactericidal, fungicidal, algicidal, and viricidal against lipophilic viruses. Silicone quaternary ammonium salt compounds are well known as exemplified by U.S. Pat. No. 3,560,385, issued Feb. 2, 1971, and the use of such compounds as antimicrobial agents is taught, for example, in a wide variety of patents such as U.S. Pat. Nos. 3,730,701, issued May 1, 1973, and 3,817,739, issued June 18, 1974, where the compounds are used to inhibit algae; 3,794,736, issued Feb. 26, 1974 , and 3,860,709, issued Jan. 14, 1975, where they are employed for sterilizing or disinfecting a variety of surfaces and instruments; 3,865,728, issued Feb. 11, 1975, where the compounds are used to treat aquarium filters; 4,259,103, issued Mar. 31, 1981; and in British Patent No. 1,386,876, of Mar. 12, 1975. Published unexamined European Application No. 228464 of July 15, 1987, teaches that microorganisms on plants can be killed by the application thereto of an aqueous mixture of a surfactant and an organosilicon quaternary ammonium compound. In a particular application of an antimicrobial silicone quaternary ammonium compound, a paper substrate is rendered resistant to the growth of microorganisms in U.S. Pat. No. 4,282,366, issued Aug. 4, 1981. In U.S. Pat. No. 4,504,541, issued Mar. 12, 1985, an antimicrobial fabric is disclosed which is resistant to discoloration and yellowing by treatment of the fabric with a quaternary ammonium base containing an organosilicone. U.S. Pat. No. 4,615,937, issued Oct. 7, 1986, as well as its companion U.S. Pat. No. 4,692,374, issued Sept. 8, 1987, relate to wet wiper towelettes having an antimicrobial agent substantive to the fibers of the web and being an organosilicon quaternary ammonium compound. In a series of Burlington Industries, Inc. U.S. Pat. Nos. 4,408,996, issued Oct. 11, 1983, 4,414,268, issued Nov. 8, 1983, 4,425,372, issued Jan. 10, 1984, and 4,395,454, issued July 26, 1983, such compounds are disclosed to be useful in surgical drapes, dressings, and bandages. This same assignee also discloses these compounds as being employed in surgeons' gowns in U.S. Pat. Nos. 4,411,928, issued Oct. 25, 1983, and 4,467,013, issued Aug. 21, 1984. Organosilicon quaternary ammonium compounds have been employed in carpets, in U.S. Pat. No. 4,371,577, issued Feb. 1, 1983; applied to walls, added to paints, and sprayed into shoes, in U.S. Pat. No. 4,394,378, issued July 19, 1983; applied to polyethylene surfaces and used in pillow ticking in U.S. Pat. No. 4,721,511, issued Jan. 26, 1988; in flexible polyurethane foams of fine-celled, soft, resilient articles of manufacture in U.S. Pat. No. 4,631,297, issued Dec. 23, 1986; and mixed with a surfactant in Japanese Kokai Application No. 58-156809, filed Aug. 26, 1983, of Sanyo Chemical Industries, Ltd., for the purpose of achieving uniformity of distribution of the compounds to a surface. Thus, the versatility of such compositions is readily apparent.
A defoamer or antifoam agent is a material which, when added in low concentration to a foaming liquid, controls the foam problem. The defoamer equilibriates the rate of foam collapse with the rate of foam formation. Such materials, in addition, remove unsightly and troublesome surface foam, improve filtration, watering, washing, and drainage, of various types of suspensions, mixtures, and slurries. Defoamers have found application traditionally in such areas of use as the pulp and paper industry, paints and latex, coating processes, fertilizers, textiles, fermentation processes, metal working, adhesive, caulk and polymer manufacture, the sugar beet industry, oil well cement, cleaning compounds, cooling towers and in chemical processes of varied description such as municipal and industrial primary and secondary waste water treatment facilities. It is essential for a defoamer that it be inert and not capable of reacting with the product or system in which it is used, and that it have no adverse effect on the product or system. The components of a defoamer generally consist of primary and secondary antifoam agents, a carrier, an emulsifier, and optionally a stabilizing agent. The primary antifoam agent is the main ingredient of the defoamer and includes materials such as hydrophobic silica treated silica, fatty amides, hydrocarbon waxes, and fatty acids and esters. In particular, hydrophobic silica is finely divided silica coated with chemisorbed silica. The silica is dispersed in hydrocarbon oil and the hydrophobic silica particles present a low energy silicon surface to the foamed environment. In the absence of the hydrocarbon oil, hydrophobic silica itself has no defoaming capacity. The secondary antifoam agent acts synergistically with the primary antifoam agent and includes such materials as silicones, and fatty alcohols and esters. Carriers frequently comprise hydrocarbon oils, water, fatty alcohols and esters, and solvents. Emulsifiers such as esters, ethoxylated compounds, sorbitan esters, silicones, and alcohol sulfates, function to spread or introduce the primary and secondary antifoam agents and the carrier into the system. Shelf life of defoamers can be improved by stabilizing agents, and often in water-based defoamers, a preservative is added to prevent bacterial spoilage in the drum or shipping container. Such stabilizing agents have consisted of, for example, oleic acid, hexylene glycol, fatty alcohols, naphthalene sulfonates, butyl alcohol, and formaldehyde. Dispersion defoamers are finely divided particulates in insoluble vehicles such as mineral oils, kerosene, fatty alcohols, and silicone oils. Representative of such dispersion defoamers are, for example, U.S. Pat. No. 3,652,453, issued Mar. 28, 1972, U.S. Pat. No. 3,677,963, issued July 18, 1972, U.S. Pat. No. 3,923,683, issued Dec. 2,1975, and U.S. Pat. No. 4,021,355, issued May 3, 1977. The dispersed particulate has a high surface area such as silica, talc, clay, fatty amides, heavy metal soaps, and high melting point polymeric materials. Representative of such materials is U.S. Pat. No. 2,843,551, issued July 15, 1968. Such particulates are treated with silicones, for example, to render them hydrophobic, as taught in U.S. Pat. No. 3,951,883, issued Apr. 20, 1976. Finely divided particles of silica may also be dispersed in polydimethylsiloxane and similar type silicones as taught, for example, in U.S. Pat. No. 4,400,288, issued Aug. 23, 1983.
As noted above, the defoamers of the prior art have often required the addition to drums and shipping containers of a preservative such as a biocide in order to prevent bacterial spoilage. This additional and separate step in the process has often proved to be cumbersome and expensive, and has not altogether been effective in that it so often overlooked entirely resulting in large batches of spoiled materials. This invention seeks to overcome such difficulties by providing an all inclusive defoamer that requires no separate step of preservative addition to drums, shipping and storage containers, but which improved defoamer includes in the defoamer composition itself, an antimicrobial agent in order to prevent microbiological contamination and deterioration of drums, shipping containers, and storage containers, of defoamer material due to bacterial spoilage. Thus, the defoamer of the present invention includes a biologically active and bactericidally active component which will combat microorganisms by either destroying all of the microbes present or preventing their proliferation to numbers that would be significantly destructive to the system sought to be protected. Hence, the defoamer of the present invention will not only perform its defoaming function but will in addition dispose of organic growths, microbes, microorganisms, bacteria, and fungi, by interfering with the metabolic process of such organisms typically found in defoamer drums, shipping containers, and storage containers, to provide lethal exposure and an inhibiting and killing action of the bacteria responsible for spoilage of such products.